To solve this problem, we need to find the acceleration of the briefcase when a force of 45 N is exerted upward on a 2.0-kg briefcase. Here's how to approach it step-by-step:

Formula

The net force $F_{net}$ acting on an object is related to its mass $m$ and acceleration $a$ through Newton's second law:

$F_{net} = m \cdot a$

However, the upward force must overcome the downward gravitational force. The net force is given by:

$F_{net} = F_{upward} - F_{gravity}$

Where:

• $F_{upward} = 45 \, \text{N}$ (force exerted upward),
• $F_{gravity} = m \cdot g = 2.0 \cdot 9.8 = 19.6 \, \text{N}$,
• $m = 2.0 \, \text{kg}$,
• $g = 9.8 \, \text{m/s}^2$ (acceleration due to gravity).

Step 1: Calculate the net force

$F_{net} = 45 - 19.6 = 25.4 \, \text{N}$

Step 2: Calculate the acceleration

$a = \frac{F_{net}}{m} = \frac{25.4}{2.0} = 12.7 \, \text{m/s}^2$

Final Answer:

The acceleration of the briefcase is 12.7 m/s².

Would you like me to elaborate further or assist with any additional steps? Here are some related questions:

1. How does gravitational force affect the motion of objects in free fall?
2. How would the acceleration change if the upward force increased?
3. What would happen if the upward force was less than the gravitational force?
4. Can you explain the relationship between force, mass, and acceleration?
5. How is this concept applied in real-world scenarios, like lifting objects?

Tip: Always identify all forces acting on an object before calculating net force and acceleration!